"It was one of the best days of my life. I will never forget it," she said.

"They gave me my own dressing room for the day, and even gave me signed ballet shoes to take home. It was just brilliant."

As part of the wish Tegan was given a behind-the-scenes tour of the venue by Royal Ballet dancer David Pickering, including a preview of costumes used in the Tales of Beatrix Potter.

And without knowing what was about to happen, she was taken backstage during the evening performance, given a mouse costume, and joined the professional dancers on stage.

The Cleeve School pupil said: "I couldn't believe it when they told me I was going on stage. I thought I was just trying the costume on."

Far from being fazed, Tegan was in her element. She followed the instructions of the professional dancers by getting into character, before staying for a bow at the final curtain.

She even had the chance to show off her skills with a few improvised ballet steps, impressing choreographers so much she was left on stage for longer than initially planned.

The youngster was showered with gifts from the other dancers including a range of Beatrix Potter goodies and bunches of flowers.

Tegan's Mum Carol said: "I never dreamt that anything could be so special. It brought tears to my eyes seeing her up on stage.

"Tegan has been through a lot with her illness. She's still very poorly and has to take regular medication. But the whole experience has given her a huge lift. She was made to feel like the star of the show.

"I want to thank the team at the Royal Ballet and Make-A-Wish Foundation for making it such a special day."

The Make-A-Wish foundation, which is based in Surrey, aims to make dreams come true for 1,000 children across the UK this year.

To refer a child for a special wish or to make a donation, contact the charity on 01276 405060 or visit www.make-a-wish.org.uk.